This invention relates to a control for an electron beam welder to maintain the point of impact of the electron beam in the intended weld line between two weldments and to maintain a predetermined beam area.
The electron beam must be in the area weld line with precision if advantage is to be taken of the electron beam. Such precision is not difficult to obtain if the weld line has a simple geometric shape; however, it becomes difficult to obtain if the weld line between weldments is irregular or because of the imprecision with which the weld line is known.
Several systems have been devised to maintain the electron beam in the intended weld line. A typical one, for example, is illustrated and described in U.S. Pat. No. 3,743,776 wherein back scattering of the electrons on opposite sides of the beam is used to maintain the electron beam in the intended weld line.